NEARLY five years after he was appointed as Kevin Rudd's full-time fuel "cop", support for the nation's Petrol Commissioner is running on empty.

As frustrated commuters suffer increasing pain at the pump, Joe Dimasi cannot point to a single major achievement since assuming the role and has lost the backing of key motoring groups.

Amazingly, Mr Dimasi still insists he isn't actually the Petrol Commissioner, years after an official press release declared him just that. And now, even the Prime Minister's office is trying to rewrite history.

Asked whether the Government considers Mr Dimasi to be the Petrol Commissioner, Mr Rudd's office issued a statement that avoided using the title, instead calling him "Commissioner to the ACCC with special responsibility for fuel related issues."

There was no such fudging on October 1, 2008, when the Government triumphantly declared the appointment of Mr Dimasi as "ACCC Petrol Commissioner".

In opposition, Mr Rudd proposed the role would be a "full-time petrol cop on the beat" because "Labor believes the federal government has a duty to do everything in its power to ensure that motorists aren't paying one cent more on petrol than is necessary".

Motoring groups across the country and the overarching Australian Automobile Association expressed bemusement over Mr Dimasi's backing away from the title and from problems in the petrol market.

"It's been a waste of time ... political window-dressing," said AAA executive director Andrew McKellar.

NRMA president Wendy Machin said: "We all feel it's been an experiment that's failed, sadly, to the detriment of competition and consumers."

Multiple motoring groups said the commissioner should be investigating potential price gouging in Coffs Harbour in NSW, Port Augusta in SA and in Darwin, to name just a few locations.

"The margins in Darwin are ridiculous," said RACQ public policy manager Michael Roth.

And that's not all. Nationally, retail "margins have been rising", said CommSec economist Savanth Sebastian. Over the last 12 months the national retail margin averaged 9.3c compared to 8.2c for the past five years, he said.

The Royal Automobile Club of WA said motorists there were being overcharged 3c a litre - or $500,000 a week.

The NRMA's Ms Machin said: "Why isn't someone forcing the oil companies to front up and tell us what they are doing?"

Ms Machin and others said the commissioner role needed to be strengthened, or scrapped.

The Coalition will abolish the role if elected.

"There's more substantial and meaningful action that can be taken rather retaining the shingle of Petrol Commissioner," said Opposition competition policy spokesman Bruce Billson.

This included giving consumers access to the same information oil companies were sharing between themselves and examining whether the laws at the ACCC's disposal were tough enough.

The PM's spokeswoman said: "The Government is committed to making sure that the watchdog, the ACCC, has the powers it needs to enforce our competition and consumer laws."

Mr Dimasi wasn't available for interview. In writing, he was asked to nominate three major successes. The response was this ACCC statement: "Along with the other commissioners, Mr Dimasi is responsible for all of the activities of the ACCC. Mr Dimasi oversees the commission's work on fuel monitoring, but also chairs the commission's committee that deals with regulated access and pricing matters.

"As the commission has previously indicated, it currently has major investigations in relation to information sharing in the fuel sector and in relation to shopper dockets. We expect these investigations to be completed later this year."

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